Tobacco smoking is the leading preventable cause of cancer mortality. Pharmacotherapy and behavioral counseling have demonstrated independent and additive effects toward aiding smoking cessation; however, counseling is rarely chosen by smokers. In contrast, minimal self-help interventions, such as smoking cessation pamphlets or booklets have much wider potential reach, yet their efficacy has been largely disappointing, with incremental abstinence rates averaging only 1 percent. Given the high dissemination potential, any significant improvement in the efficacy of self-help would have high public health impact with respect to smoking and smoking related illness and mortality. In contrast to traditional self-help, a notable exception to the historically poor efficacy of self-help has been extended self-help that provides evidence-based content over a prolonged period of time. A recently completed trial of such an intervention, comprising 18 months of contact with a written social support component, revealed high efficacy throughout the 24-month follow-up period, as well as high cost- effectiveness. Wide-scale implementation and public health impact would be enhanced by the availability of a Spanish-language version to reach the largest and fastest growing ethnic minority population of smokers. The current smoking prevalence among Hispanic/Latino adults varies by cultural subgroup, with prevalence above 30 percent, for example, among those of Puerto Rican and Cuban descent. Greater smoking prevalence is also associated with lower income and education, and greater US acculturation. Prior research has demonstrated that Hispanic/Latino smokers face unique challenges such as lower awareness and acceptability of pharmacotherapies and less assistance with smoking cessation from their health providers. The goal of this study is to address this gap in cessation by conducting a randomized clinical trial to test the efficacy of a culturally appropriate Spanish-language version of the existing validated self-help intervention. The efficacy of this intervention will be tested against two control conditions. The first, Usual Care, will consist of a traditional self-help intervention in Spanish. The second, Contact Control, will match the novel intervention on time and contact. These two control conditions address external and internal validity, respectively. It is hypothesized that, compared to both the Usual Care and the Contact Control conditions, the intervention will produce higher abstinence rates throughout 24 months of outcome assessment. Potential moderator variables will be evaluated to guide further refinement and targeting of the intervention. This would be the first study to test a Spanish-language adaptation of a validated self-help smoking cessation intervention in a nation-wide RCT. If efficacy is demonstrated in this study, a low-cost, easily disseminated, evidence-based intervention would be available, with the potential to reduce ethnic health disparities associated with tobacco smoking.